If only there were some method by which we could disaggregate effects like these... Perhaps we could get a huge number of people and then randomly assign some

If only there were some method by which we could disaggregate effects like these... Perhaps we could get a huge number of people and then randomly assign some of them to a "treatment" group and then some to a "control" group. We don't tell people which group they're in. Then we measure whether they got wet. Just a thought...